Conductive patterns and tracks are used in a wide variety of electronic devices, e.g. as circuitry. Such conductive tracks are produced by depositing conductive metal complexes on a wide variety of substrates or carrier mediums. First, a precursor metal complex is applied to the substrate. By a curing or reducing step the metal complexes are converted into pure, conductive metal. The patterns can be easily applied by printing methods, e.g. ink-jet printing. The metal complexes which are employed as inks need to have a certain viscosity to be printable.
Metal complexes for printing conductive patterns are known.
US2007/0096064 claims a process for forming conductive features for solar cells. The precursor composition which is applied to obtain said features has a low viscosity of not greater than about 1000 Cps and can also have a low conversion temperature. The low viscosity precursor composition can comprise organic ligands bound to metal salts.
US2010/0021704 describes an organic silver complex in which an organic ligand containing an amine group and a hydroxyl group is bonded with aliphatic silver carboxylate at an equivalent ratio of 2:1 to form a complex. The complex occurs in form of a paste.
US2011/0023658 refers to a method for producing silver nano cubes from a solution comprising at least one polyol, at least one silver compound and at least one organic protective agent. The silver compound is a silver salt while the organic protective agent is a compound which does not react with the polyol. The polyol has at least two hydroxyl groups and is able to reduce the silver compound to silver at elevated temperatures. The product of the reaction of the compounds are solutions which comprise silver nano cubes. These cubes are not employed for printing but are instead used in nano-scale ferromagnetic applications. This document does not reveal how the viscosity of metal complex solutions can be adjusted.
JPH11315241 discloses an inkjet ink composition comprising a liquid containing an organometallic complex metal component and a resin. For the purpose of adjusting the viscosity, the ink is used in the form of an aqueous solution containing a water-soluble resin, such polyvinyl alcohol, polyethylene oxide and methylcellulose.
JPS6473082 discloses a plating paint containing metal ions, a reducing agent for the metal ions, a solvent of the metal ions and a viscosity imparting agent, the latter being exemplified by polyethylene glycol, casein and glue. The viscosity of the plating paint is set at about 0.3-0.4 Pas.
KR20070058816 discloses a silver organo-sol ink comprising as an organic solvent a reactive organic solvent which is said to form a chelating agent or a complex with silver, and a polar or non-polar dilution solvent for controlling viscosity.
CN102863845 discloses a silver-organic conductive ink comprising a saturated carboxylic acid silver compound, an amido compound, a solvent and a thickening agent. The thickening agent is used for adjusting viscosity.
CN101523508 discloses an organic silver complex compound in which an organic ligand containing an amine group and a hydroxyl group is bonded to aliphatic silver carboxylate at an equivalent ratios of 2:1 to form a complex.
None of the prior art documents teaches how the viscosity of such metal complexes can be adjusted and fine-tuned in general and how a printing ink comprising a metal complex with a specifically desired viscosity can be achieved.